DIY Cold Brew Concentrate-Make it at Home

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There are loads of ready made cold brew concentrates on the market these days but over time, buying them at the grocery store can get a little bit pricey.

If you are looking to save a little money, it’s actually very simple and economical to make your own cold brew coffee concentrate at home. You don’t even need any special equipment. Let me show you how to DIY it.

What is the difference between cold brew and cold brew concentrate

The main difference between cold brew coffee and cold brew concentrate is the ratio of coffee to water.

Now I hate those articles that make you wait for the recipe, but I do want to clear up one thing before we get to the actual process and that is the difference between cold brew coffee and cold brew concentrate.

I see a lot of recipes out there for cold brew coffee and it can be confusing because some of them yield a coffee that’s ready to drink and some yield a concentrate, and they don’t necessarily tell you which it is.

Cold brew coffee is made with a ratio where once strained it can be drunk immediately without any further modifications.

Cold brew concentrate is meant to be diluted with water. This can be an advantage in recipes and is also perfect for people who like to adjust the strength of their coffee. Maybe she likes it strong and he likes it less strong. No problem, make a concentrate and everyone can dilute it to suit their own tastes.

A concentrate is also useful if you’re planning to add milk or other flavorings such as creamers while still maintaining a bold coffee flavor.

Typically, a concentrate is diluted 50/50 with water however some commercial products are even stronger than this. For example, Starbucks Cold Brew capsules (affiliate link, Amazon) are diluted into 8 ounces of water but only contain 1.35 ounces of concentrate. (I love these for traveling as I can easily make cold brew in my hotel room and I don’t even need a fridge).

A concentrate is also useful if you are making a hot cup of coffee, but prefer the flavor of cold extraction. Just add hot water to your concentrate instead of cool water.

Notes for making great cold brew concentrate

Making cold brew concentrate is really no different than making cold brew coffee other than we will use much more coffee in relation to water. It’s all about proportions.

DIY Concentrate: I have experimented with various ratios and I have yet to create a good tasting concentrate at home that can be diluted 50/50 with water like commercial concentrates.

Use too much coffee and the water gets absorbed by the coffee grounds, which isn’t useful. Using more coffee than this recipe tends to create a bitter, unpleasant flavor.

Now, here’s the caveat: I like a strong black cold brew (think Starbucks) so your mileage may vary but I find that 2 parts of this concentrate and 1 part water is about right for me. The awesome thing about using a concentrate is you can adjust it to your preference by adding more or less water.

Here’s the process in a little more detail:

Each of these sections expands on the steps in the recipe above.

Step 1. Tips on Coffee Grind

Coarse grounds work best in cold brew because we don’t want to over-extract the coffee. Using coarse grounds reduces the surface area of coffee in contact with the water. If you are able to, grind whole coffee beans yourself right before use for the freshest results.

If you don’t have a grinder, look for pre-ground coffee designed for cold brew which will usually already be coarsely ground. Don’t worry if you can’t find it though, regular ground coffee will work, but you may want to reduce steep time to 12-14 hours to compensate for the finer grind.

Step 2-4. Why pre-wet the grounds and add the water in stages?

One problem when mixing coffee with water is ensuring all the grounds are in contact with the water. This can particularly be a problem with pour over and drip methods of extraction where some of the coffee grounds may remain completely dry at the end—such a waste.

Just like making a gravy from a powder mix, mixing the coffee with a little water first helps to wet all the grounds evenly and then we can top it up with the remaining water. This helps to prevent pockets of dry grounds.

Step 5: Extraction safety and adjusting time and temperature

You can extract cold brew in as little as 2 hours at room temperature (theoretically), or up to 24 hours in the fridge. I recommend using the fridge because anything with water can quickly start to grow micro-organisms.

Microbial growth slows at cooler temperatures and organisms are killed at very high (boiling) temperatures. Room temperature extraction is at temps that make for an ideal breeding ground.

Read more about brewing in the fridge vs. room temperature

For best flavor, 14-20 hours is my recommendation.

Here’s what happens during steeping:

• 0-8 hours: Initial extraction begins
• 8-16 hours: Primary flavor development
• 16-18 hours: Peak flavor achievement
• Beyond 20 hours: Risk of over-extraction

Why this timeline matters:

• Under 16 hours: Often tastes underdeveloped
• 16-18 hours: Perfect balance of flavors
• Over 20 hours: Can become bitter.

Time and temperature are two important variables in making cold brew. Lower temperatures such as brewing in the fridge means longer steeping times. There is a diminishing return though, if you steep for too long you can end up with over-extracted coffee, which can be bitter.

Step 6: Best filter to use

A paper coffee filter or fine nut milk bag work best for straining coffee. I find paper works the best and provides a nice clear coffee with little to no residue.

A nut milk bag is a great eco-friendly (re-usable) option but can be difficult to keep clean. Coffee tends to get caught in the seams. I don’t recommend cotton bags, as even after repeated washing I find my coffee tastes a little like chewing on a washcloth.

Read more about the best coffee filter bags

Step 7: Preparing your coffee to drink

When you are ready to drink, add concentrate to a glass. Add any ice cubes, and top it off with water. Taste test and add more concentrate if it is too weak, or more water if it is still too strong.

More Q & A

What is the best ratio of coffee to water for cold brew concentrate?

Opinions on this vary, but I find that one part coffee to three parts water makes a concentrated brew that can be diluted 2:1 with water (2 parts coffee:1 part water) to create a strong, regular to drink brew.

I also find using a ratio like this instead of measurements makes it super simple to make any amount. No need to get out the scale to weigh your coffee and you can make as little or as much as you want. Just keep the 1:3 coffee to water ratio. For example, make a bigger batch by using 2 c. of coffee and 6 c. of water.

What about 2 parts water and 1 part coffee? I’ve tested this and the TDS (total dissolved solids) was actually lower at this ratio than 3:1. Why? It’s all about water movement and extraction efficiency.

Here’s what happens with different ratios:

• Too concentrated (1:2 or stronger): Water can’t move freely between grounds
• Perfect range (1:3 to 1:4): Optimal extraction and movement
• Too diluted (1:5 or weaker): Results in underdeveloped flavors.

Ooh, tell me more about TDS!

Total Dissolved Solids (TDS) is an important measurement in coffee brewing. It tells us how much coffee material has been extracted into the water.

Using more coffee doesn’t always mean higher TDS. In fact, testing shows that TDS can actually decrease when too much coffee is used relative to water. Here’s why:

• Water needs space to move between coffee grounds
• Overcrowded grounds prevent proper extraction
• Optimal extraction requires proper contact time

Think of it like trying to wash clothes in a washing machine. If you stuff too many clothes in, the water can’t move freely, and nothing gets properly clean.

The sweet spot for cold brew concentrate are TDS readings between 2.5% and 3.5%

Factors that affect TDS include grind size, steeping time, water temperature, coffee-to-water ratio, and bean roast level.

What kind of roast should I use?

Different roasts will yield different flavors. I recommend a medium roast coffee for cold brew, but it really is personal preference. Dark roasts may yield a more burnt and bitter flavor.

Do I need to grind the beans myself?

The best coffee, hot or cold, comes from freshly roasted beans that have been ground right before use.

Evenly ground coffee prevents uneven extraction (where the fine particle extract more quickly and lend bitter flavors to your brew). A mixture of particle sizes also means it will be easier to filter your coffee and not have any sediment.

If you don’t have access to a coffee grinder, you can use pre-ground coffee. Just check the date on the package and try to use coffee that has been roasted within the past 2 months. Just remember that most ground coffee from the store is medium grind and so you should reduce the steeping time by a couple of hours.

Why Coarse Grind?

Coarse ground coffee is important for cold brew concentrate for several reasons:

• Better Water Flow: Allows water to circulate freely
• Prevents over-extraction and helps produce a consistent flavor
• Easier Filtration: Less sediment in final product, which leads to a cleaner taste

Think of your coffee grounds like rocks in a river. Large rocks (coarse grounds) let water flow smoothly around them, while pebbles (fine grounds) can create blockages and muddy water. The ideal grind size should look similar to raw sugar, sea salt, or coarse breadcrumbs.

The Importance of Water Quality

Water is the other main ingredient in your cold brew concentrate, yet it’s often overlooked. Using the right water can dramatically improve your results. 

Filtered water is essential for several reasons:

• Removes chlorine taste
• Eliminates unwanted minerals
• Provides consistent results
• Enhances coffee flavors

Avoid using distilled water as some mineral content is needed to properly extract the coffee compounds, plus distilled water tastes flat.

Remember: the best coffee beans can’t overcome the limitations of poor water quality. If you’re going to invest in one thing, a good water filter is worth considering.

How long will my concentrate keep in the fridge?

Many people say that cold brew can be kept in the fridge for up to 2 weeks. This is because some of the oils that can go rancid are not extracted in cold brew.

Yet, due to the issues with water being a breeding ground for little beasties that I explained above, I recommend only making enough for no more than 1 week. But, if you want the best flavor make it in small batches and consume within a day or two.

Why should I make a concentrate instead of ready-to-drink? What else can you make with cold brew concentrate?

Here are some advantages to making your own concentrate:

• Save space in fridge. Since this is a concentrate you can put it in a container that’s half the size that you would need for ready to drink strength.

• Make more coffee per batch. Instead of brewing for a day or two at a time you can brew for four to seven days with one batch if you want.

• For recipes. Concentrate is great for recipes like frappes, protein shakes, or to substitute in any recipe that calls for espresso.

As you can see, making a cold brew concentrate is no more complicated than any home cold brew. Just adjust the proportions to a three to one ratio of water to coffee and you are good. And remember my cardinal rule of home brewing:

If you brew it too strong, you can always dilute it but if you make it too weak, it’s a write-off.

So, don’t skimp on the coffee and have fun!

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